The present invention relates to concrete cores used in the fabrication of concrete pipe, and, more in particular, to such a core and a gate used to open and close it.
A core of a concrete mold defines the interior surface of a concrete pipe. During casting, the core provides a barrier for wet concrete. After casting, it is necessary to break down the core and remove it. This requires a reduction of the core's diameter so as to free it from the interior walls of the cast pipe. In the past, concrete pipe cores have been contractable to a smaller diameter for withdrawal from a cast pipe. During the casting process the core has to be of adequate strength to withstand the radial inward pressure placed on it by concrete. Wedges have been used to lock the core gates closed. Existing techniques requiring personnel to drive wedges and the like constitute a safety hazard.